Armchair Boron Nitride Nanoribbons Research Articles

Hexagonal boron nitride nanoribbon as a novel metal-free catalyst for high-efficiency NO reduction to NH3

Electrochemical NO reduction is taken as a promising avenue to eliminate detrimental NO into valuable NH3 for a balanced nitrogen cycle. Current electrocatalysts for NO reduction are mainly focused on metal-bearing catalysts, while metal-free catalysts with low cost, excellent stability, activity and selectivity are strongly desired. Herein, we report hexagonal boron nitride nanoribbons (BNNRs) as novel metal-free catalysts for efficient NO adsorption and reduction into NH3. Our results reveal that bare edge B atoms of armchair and zigzag BNNRs act as active sites for spontaneous chemisorption and activation of NO, originating from significant electron transfer. Notably, in the subsequent NO reduction, NH3 can be spontaneously produced by armchair BNNR with a limiting potential (UL) of 0 V, which is superior to most well-established single-atom, biatom and pure traditional metal catalysts. The awesome catalytic activity for NO reduction is intrinsically introduced by the suitable NO adsorption strength on armchair BNNR, which is illuminated to appropriate electronic interactions between the active site and NO. Moreover, the catalytic selectivity of armchair BNNR for NH3 production at both low and high NO coverage can be well guaranteed due to the higher thermodynamic energy barriers in generating N2O, N2 and H2. Overall, our findings pioneer the catalytic application of BNNR and unveil the veil of metal-free catalysts for direct NO reduction to NH3.

On the effect of local torsion on the electromechanical properties of armchair boron nitride nanoribbons

Similar to graphene nanoribbons, boron nitride nanoribbons are prone to twist intrinsically. Hence, investigating the effect of local torsion on the electromechanical properties of boron nitride nanoribbons (9-cells) is of great importance. By using the density functional theory in combination with the non-equilibrium Green’s function method, the effect of local torsion on the structural evolution and electrical transport of armchair boron nitride nanoribbons is investigated here. In addition, the electrical transport, current–voltage and Local density of state (LDOS) are studied. It is shown that local twist can change the transport properties of the boron nitride nanoribbons significantly. The current at a given bias can switch on/off or change many times with twist angle, which is related to twist-induced changes in electronic structures of boron nitride nanoribbons. The results of the current work can provide a valuable guideline for design and implementation of boron nitride nanoribbons in nanoelectromechanical systems and devices.

The carrier mobility and sizable bandgap influorinated armchair boron nitride nanoribbons

The electronic transport properties of two-dimensional materials are strongly influenced by the charge carrier mobility and the energy bandgap. Furthermore, the carrier-phonon interaction governs the electrical response of any electrical device at a specific temperature. In light of this, the electron mobility and energy bandgap of fluorine (F) doped armchair Boron Nitride nanoribbons (a-BNNRs) are computed theoretically and analysed further. The acoustical deformation potential (ADP) scattering mechanism is taken into account to determine the mobility of the system. The calculations are carried out in presence of an applied electric field as well as different doping concentrations across a specified temperature range (200–300 K). The computed value of electron mobility for F-BNNR is of the order 104 cm2 V−1 s−1. Such higher magnitude of electron mobility suggests the semiconducting nature of BNNRs. Moreover, the variation of electron mobility as a function of temperature and doping concentration demonstrates a significant reduction in the acoustical phonon-limited electron mobility of fluorine-doped boron nitride nanoribbons. To estimate the energy bandgap, a set of equations are determined from the Fermi velocity expression using the nearly free electron (NFE) model. The computed energy bandgap is found to diminish with the increasing size of the nanoribbon. This behaviour of F-doped a-BNNRs envisages its applications in Visible-IR optical sensors.

Effect of Edge Fluorination on Electronic and Transport Properties of Aarmchair Boron Nitride Nanoribbons: A First-Principles Study

We have systematically investigated the effect of edge fluorination on structural stability, electronic and transport properties of armchair boron nitride nanoribbons (ABNNRs), using first-principles calculations within the frame work of local spin-density approximation (LSDA). ABNNRs with F-passivation on only edge B atoms, regardless of their width, are found to be half-metallic and energetically most stable. For these ribbons, completely spin polarized charge transport is predicted across the Fermi level as a result of giant spin splitting. Transmission spectrum analysis also confirms the separation of spin-up and spin-down electronic channels. It is revealed that F-passivation of only edge N atoms transforms nonmagnetic bare ribbons into magnetic semiconductors whereas fluorination of both the edges does not affect the electronic and magnetic state of bare ribbons significantly. Predicted Half-metallicity projects these ABNNRs as potential candidates for inorganic spintronic devices.

Thermoelectric properties study on the BN nanoribbons via BoltzTrap first-principles

Thermoelectric materials have attracted the attention of scientists because they directly convert waste heat of electric energy into valuable electrical energy. In recent years, the boron nitride structure has attracted much attention due to its thermoelectric properties and environmental friendliness. In this paper, the thermoelectric properties of boron nitride nanoribbons were simulated and analyzed, discovering that the figure-of-merit (ZT) value of armchair boron nitride nanoribbons is much better than that of zigzag boron nitride nanoribbons. Subsequently, we discuss the bandwidth effects and edge chirality on two important thermoelectric properties, Seebeck coefficient and ZT. Although edge passivation has been carried out, different edge chiralities still have a significant impact on carrier transport. The development of boron nitride-based materials will clarify their potential for developing high performance next generation thermoelectric devices.

Effect of substitutional defects on resonant tunneling diodes based on armchair graphene and boron nitride nanoribbons lateral heterojunctions

A nanometer-scaled resonant tunneling diode based on lateral heterojunctions of armchair graphene and boron nitride nanoribbons, exhibiting negative differential resistance is proposed. Low-bandgap armchair graphene nanoribbons and high-bandgap armchair boron nitride nanoribbons are used to design the well and the barrier region, respectively. The effect of all possible substitutional defects (including BC, NC, CB, and CN) at the interface of graphene and boron nitride nanoribbons on the negative differential resistance behavior of the proposed resonant tunneling diode is investigated. Transport simulations are carried out in the framework of tight-binding Hamiltonians and non-equilibrium Green’s functions. The results show that a single substitutional defect at the interface of armchair graphene and boron nitride nanoribbons can dramatically affect the negative differential resistance behavior depending on its type and location in the structure.

Bipolar magnetic semiconductor properties and spin-dependent Seebeck effects induced by nanoscale graphene domains doped into armchair boron nitride nanoribbons

Inspired by the synthesis of nanometer-scale graphene quantum dots via a doping process in boron nitride (BN) sheets (Adv. Mater. 2019, 1805778), we investigated the magnetic and thermal spin transport properties of armchair BN nanoribbons containing nanoscale graphene domains. It was found that both M-QB and M-QN structures were bipolar magnetic semiconductors (BMSs). Two spin caloritronics devices were designed on the basis of the 15-6B and 15-6N nanoribbons. Spin-dependent Seebeck effects, spin-dependent Seebeck diode effects and thermoelectric diode effects were observed in these devices. This work provides theoretical guidance for the design of new spin caloritronics devices.

Magneto-EELS of armchair boronitrene nanoribbons.

The evolution of the electron energy loss spectrum (EELS) of ultranarrow armchair boron nitride nanoribbons (aBNNRs) during low and high photon energy transfers has been studied theoretically when a magnetic field and temperature gradient are applied. In order to achieve this goal, the widely used linear response theory within the Green’s function theory was employed. Here, using the EELS we show that σ ↦ σ* or π ↦ π* and σ ↦ π* or π ↦ σ* excitations corresponding to the intraband and interband transitions, respectively, can be tuned by ribbon width, magnetic field, wave vector transfer, and temperature. A comparison with experimental studies reveals that for realistic ribbon widths, i.e. 10–100 nm, both excitations are weak. However, we observe that only transitions between the same states, i.e. σ ↦ σ* or π ↦ π* can be controlled with a magnetic field due to the localized highest occupied and lowest unoccupied states at low-energy regions and different states are not influenced when the magnetic field is applied. Interestingly, the detailed shape of the magneto-EELS of the 7-aBNNR indicates a direct-to-indirect band gap transition when the wave vector transfer is perpendicular to the 7-aBNNR plane. Finally, we discover that there is an anomalous behavior for the temperature dependence of the magneto-EELS in general. The present work brings forward the understanding of the magneto-EELS of ultranarrow aBNNRs under different environmental conditions for logic applications in nanoplasmonics.

Resonant Tunneling Diode by Means of Compound Armchair Boron/Nitride and Graphene Nanoribbons

The band gap of armchair graphene nanoribbons (AGNRs) can be modulated by replacing the carbon atoms with boron/nitride (BN) atoms to produce the compound nanoribbons, while the width of ribbons remains constant. By introducing BN doping atoms in the proper positions along the ribbon length, a double-barrier quantum-well structure is constructed. Consequently, negative differential resistance properties can be obtained by a combination of armchair BN nanoribbons (ABNNRs) and AGNRs as the compound ABNxGyNRs, in which x and y denote the number of BN and C atoms in the ribbon width, respectively. The proposed resonant tunneling diode (RTD), called an armchair BN graphene nanoribbon resonant tunneling diode (ABNGNR-RTD), is investigated in three different platforms including W, S, and H shapes. The numerical tight-binding model along with non-equilibrium Green’s function formalism is taken into account to study the electronic properties of the proposed RTD. The performance of the ABNGNR-RTD is examined in terms of device characteristics such as peak-to-valley ratio (PVR) and power dissipation. Based on the presented results, the performance of H-shaped devices is better than those of the other two cases in terms of PVR and power dissipation. In addition, the electronic properties of ABNGNR-RTDs can be modified by varying the relative width of ABNNRs with respect to AGNRs.

Zeeman-magnetic-field–induced magnetic phase transition in doped armchair boron-nitride nanoribbons

In this work, the magneto-charge structure factor (CSF) of hexagonal doped armchair boron-nitride nanoribbons (ABNNRs) has been addressed using the tight-binding Hamiltonian model and the Green's function technique. In particular, we study the charge static susceptibility in the presence of the Zeeman magnetic field. The calculations of the correlation function of charge densities lead to magnetic phase transitions, which are explained by the temperature-dependent magneto-CSF. We have observed different width-dependent CSF treatments in the presence and absence of magnetic field for both undoped and doped ABNNRs. Depending on the magnetic field strength, transitions from antiferromagnetic to the ferromagnetic (paramagnetic) arrangement of spins has been established for undoped (doped) ABNNRs. We have found that, furthermore, in addition to the magnetic field, the magnetic phase can be controlled by the concentration and incoming momentum of electronic dopants. These results have direct implications for the control of the dopant and magnetic field for the practical realization of boron-nitride nanoribbons-based spintronic applications.

Insulator-semimetallic transition in quasi-1D charged impurity-infected armchair boron-nitride nanoribbons

We address control of electronic phase transition in charged impurity-infected armchair-edged boron-nitride nanoribbons (ABNNRs) with the local variation of Fermi energy. In particular, the density of states of disordered ribbons produces the main features in the context of pretty simple tight-binding model and Green's functions approach. To this end, the Born approximation has been implemented to find the effect of π-band electron-impurity interactions. A modulation of the π-band depending on the impurity concentrations and scattering potentials leads to the phase transition from insulator to semimetallic. We present here a detailed physical meaning of this transition by studying the treatment of massive Dirac fermions. From our findings, it is found that the ribbon width plays a crucial role in determining the electronic phase of disordered ABNNRs. The obtained results in controllable gap engineering are useful for future experiments. Also, the observations in this study have also fueled interest in the electronic properties of other 2D materials.

Modelling boron nitride nano-structures as catalysts in fuel cells

The dissociation of O2 and HO2 are important reactions that occur at the cathode of fuel cells and require catalysts to proceed. There is a need to replace the presently used platinum catalyst with less expensive materials. Modelling has been used to identify potential two-dimensional catalysts such as boron- and nitrogen-doped graphene. Here, the possibility of boron nitride nano-ribbons and nano-tubes which do not require doping are considered. Density functional calculations are used to show that O2 and HO2 can bond to zig–zag and armchair boron nitride nano-ribbons and nano-tubes. The bond dissociation energies (BDEs) to remove an O and an OH from O2 and HO2 bonded to the boron nitride ribbons and tubes are calculated and are a measure of the catalytic effectiveness of the boron nitride structures. The results show that both the zig–zag and armchair boron nitride ribbons could be a catalyst for HO2 dissociation but not O2 dissociation. However, zig–zag boron nitride nano-tubes are shown not to be effective catalysts for the dissociation of O2 or HO2. An armchair boron nitride nano-tube is shown to have a very low BDEs to remove OH from HO2 bonded to it and could be an affective catalyst.

Magneto-electronic properties and mechano-magnetic coupling effects in transition metal-doped armchair boron nitride nanoribbons

基于密度泛函理论的第一性原理计算方法，研究了多种过渡金属（TM）掺杂扶手椅型氮化硼纳米带（ABNNR-TM）的结构特点、磁电子特性及力-磁耦合效应.计算的结合能及分子动力学模拟表明ABNNR-TM的几何结构是较稳定的，同时发现对于不同的TM掺杂，ABNNRs能表现出丰富的磁电子学特性，可以是双极化磁性半导体、一般磁性半导体、无磁半导体或无磁金属.双极化磁性半导体是一种重要的稀磁半导体材料，它在巨磁阻器件和自旋整流器件上有重要的应用.此外，力-磁偶合效应研究表明：ABNNR-TM的磁电子学特性对应力作用十分敏感，能实现无磁金属、无磁半导体、磁金属、磁半导体、双极化磁性半导体、半金属等之间的相变.特别是呈现的宽带隙半金属对于发展自旋电子器件有重要意义.这些结果表明：可以通过力学方法来调控ABNNR-TM的磁电子学特性.

Possibility of spin-polarized transport in edge fluorinated armchair boron nitride nanoribbons

Calculated DOS for edge-fluorinated. ABNNRs; featuring half-metallicity.

Electronic and Transport Properties of Armchair Boron Nitride Nanoribbons Functionalized with Chlorine

Electronic and Transport Properties of Armchair Boron Nitride Nanoribbons Functionalized with Chlorine

Half-metallicity in armchair boron nitride nanoribbons: A first-principles study

Using density functional theory, we predict half-metallicity in edge hydrogenated armchair boron nitride nanoribbons (ABNNRs). The predicted spin polarization is analyzed in detail by calculating electronic and magnetic properties of these hydrogenated ABNNRs by means of first-principles calculations within the local spin-density approximation (LSDA). ABNNRs with only edge B atoms passivated by H atoms are found to be half-metallic (regardless of their width) with a half-metal gap of 0.26 eV. Upto 100% spin polarized charge transport is predicted across the Fermi level owing to the giant spin splitting. Transmission spectrum analysis also confirms the separation of spin up and spindown electronic channels. It is revealed that H-passivation of only edge N atoms transforms non-magnetic bare ribbons into energetically stable magnetic semiconductors whereas hydrogenation of both the edges does not affect the electronic and magnetic state of bare ribbons significantly. The results are promising towards the realization of inorganic spintronic devices.

Adsorption of COCl2 gas molecule on armchair boron nitride nanoribbons for nano sensor applications

First-principle calculations under the framework of density functional theory have been performed to study the adsorption of COCl2 (Phosgene) gas molecule on armchair boron nitride nanoribbon (ABNNR). Depending upon the geometry of the ribbon, we have considered two possible cases for adsorption of guest molecule i.e. adsorption at closed edge and adsorption at open edge. Adsorption energy (Ead) calculations implies that adsorption at open edge is energetically more favorable compared to closed edge case. The formation of closed ring structure at the open edge in this case also accounts for its stability. Electronic properties reveal that with the adsorption of COCl2 molecule on ABNNR the semiconducting behavior remains intact but a significant modulation in the band gap is observed as compared to bare ribbon. The current voltage (I–V) characteristics have also been investigated using non-equilibrium green’s function (NEGF) approach. The results indicate towards the potential applicability of ABNNR for sensing the toxic COCl2 gas.

A first-principles investigation on the effect of the divacancy defect on the band structures of boron nitride (BN) nanoribbons

On the basis of the comprehensive first-principles computations, we investigated the geometries, electronic and magnetic properties of zigzag and armchair boron nitride nanoribbons (BNNRs) with the divacancy defect of 5–8–5 ring fusions formed by removing B–N pair, where the defect orientation and position are considered. Our computed results reveal that all of the defective BNNRs systems can uniformly exhibit nonmagnetic semiconducting behavior, and the formation of the divacancy 5–8–5 defect can significantly impact the band structures of BNNRs with not only the zigzag but also armchair edges, where their wide band gaps are reduced and the defect orientation and position play an important role. Clearly, introducing divacancy defect can be a promising and effective approach to engineer the band structures of BNNRs, and the present computed results can provide some valuable insights for promoting the practical applications of excellent BN-based nanomaterials in the nanodevices.

Theoretical study of the influence of the electric field on the electronic properties of armchair boron nitride nanoribbon

We have investigated the electronic properties of A-BNNRs in the external electric field using third nearest neighbor tight binding approximation including edge effects. We found that the dependence of on-site energy to the external electric field for edge atoms and center part atoms is different. By comparing the band structure in the different fields, several differences are clearly seen such as modification of energy dispersions, creation of additional band edge states and band gap reduction. By increasing the electric field the band gap reduces linearly until reaches zero and BNNRs with larger width are more sensitive than small ones. All changes in the band structure are directly reflected in the DOS spectrum. The numbers and the energies of the DOS peaks are dependent on the electric field strength.

Electronic and optical properties of boron nitride nanoribbons in electric field by the tight-binding model

The tight-binding model is used to study the electronic and optical properties of armchair and zigzag boron nitride nanoribbons (ABNNRs and ZBNNRs) in electric field. Electric field could significantly change dispersion relations, degeneracy, edge-states, band crossings, and energy gaps. The field-modulation of energy gaps is more effective and covers wider energy range for BNNRs than graphene nanoribbons. The critical electric field that induces zero-gap transition strongly depends on geometric structures of BNNRs. At zero field, the selection rule and the absorption frequency range of spectral functions are different between ABNNRs and ZBNNRs. Electric field would change state functions that constructs new selection rule and further exhibits more absorption peaks.